Biochemically defined antibodies to pancreatic beta cell antigens will be used to identify subjects who may be susceptable to develop type 1 diabetes mellitus but who are islet cell antibody (ICA) negative. Glucose tolerance tests will be performed in those subjects to assess insulin c-peptide secretion. Subjects who are biochemical antibody positive but ICA negative and who also have antibodies to adrenal gland 21-hydroxylase will have testing for adrenal gland response to ACTH.